Bi2O2CO3 Nanosheets as Electrocatalysts for Selective Reduction of CO2 to Formate at Low Overpotential

Electrochemical reduction of carbon dioxide (CO2) to formate is energetically inefficient because a high overpotential (>1.0 V) is required for most traditional catalysts. In this work, Bi2O2CO3 (BOC) nanosheets were synthesized as electrocatalysts of CO2 reduction for the first time. Additionally, BOC decorated on the glassy carbon electrode was reduced in situ to metal Bi (RB) for comparing the catalytic performance toward CO2 reduction to that of BOC. The maximum faradaic efficiency of BOC was 83% at an overpotential of 0.59 V, which is a little lower than that of RB (90% obtained at the overpotential of 0.99 V). However, the overpotential for the reduction of CO2 to formate on BOC is obviously decreased compared to that on RB. After 27 h of electrolysis, approximately 80% formate selectivity was obtained using the BOC catalyst. According to the experimental results and the related literature, a new mechanism for the CO2 reduction reaction on BOC was proposed, which may play a guiding role in future catalyst design.